Index: uma_core.c
===================================================================
RCS file: /home/ncvs/src/sys/vm/uma_core.c,v
retrieving revision 1.119.2.16
diff -u -r1.119.2.16 uma_core.c
--- uma_core.c	2 Jun 2006 09:56:27 -0000	1.119.2.16
+++ uma_core.c	10 Dec 2006 21:09:01 -0000
@@ -2016,9 +2016,12 @@
 
 			if (flags & M_NOWAIT)
 				break;
-			else
+			else {
+				vm_uma_drain_needed = 1;
 				msleep(keg, &keg->uk_lock, PVM,
 				    "zonelimit", 0);
+				vm_uma_drain_needed = 0;
+			}
 			continue;
 		}
 		keg->uk_recurse++;
Index: uma_int.h
===================================================================
RCS file: /home/ncvs/src/sys/vm/uma_int.h,v
retrieving revision 1.31.2.6
diff -u -r1.31.2.6 uma_int.h
--- uma_int.h	15 Aug 2005 09:01:11 -0000	1.31.2.6
+++ uma_int.h	10 Dec 2006 21:10:46 -0000
@@ -324,6 +324,9 @@
 #define UMA_ZFLAG_CACHEONLY	0x80000000	/* Don't ask VM for buckets. */
 
 #ifdef _KERNEL
+/* XXX Whether we want to drain UMA zones */
+extern int vm_uma_drain_needed;
+
 /* Internal prototypes */
 static __inline uma_slab_t hash_sfind(struct uma_hash *hash, u_int8_t *data);
 void *uma_large_malloc(int size, int wait);
Index: vm_pageout.c
===================================================================
RCS file: /home/ncvs/src/sys/vm/vm_pageout.c,v
retrieving revision 1.268.2.3
diff -u -r1.268.2.3 vm_pageout.c
--- vm_pageout.c	9 Mar 2006 00:02:51 -0000	1.268.2.3
+++ vm_pageout.c	10 Dec 2006 21:15:13 -0000
@@ -140,6 +140,7 @@
 
 
 int vm_pages_needed;		/* Event on which pageout daemon sleeps */
+int vm_uma_drain_needed = 0;	/* Are we low on UMA zones? */
 int vm_pageout_deficit;		/* Estimated number of pages deficit */
 int vm_pageout_pages_needed;	/* flag saying that the pageout daemon needs pages */
 
@@ -694,7 +695,27 @@
 	vm_page_unlock_queues();
 	pmap_pagedaemon_waken = 0;
 }
-	
+
+/*
+ *	vm_uma_drain drains UMA zones when necessary.
+ *
+ *	Must be called with Giant held.
+ */
+static void
+vm_uma_drain(void)
+{
+
+	mtx_assert(&Giant, MA_OWNED);
+	/*
+	 * Decrease registered cache sizes.
+	 */
+	EVENTHANDLER_INVOKE(vm_lowmem, 0);
+	/*
+	 * We do this explicitly after the caches have been drained above.
+	 */
+	uma_reclaim();
+}
+
 /*
  *	vm_pageout_scan does the dirty work for the pageout daemon.
  */
@@ -715,14 +736,7 @@
 	int maxlaunder;
 
 	mtx_lock(&Giant);
-	/*
-	 * Decrease registered cache sizes.
-	 */
-	EVENTHANDLER_INVOKE(vm_lowmem, 0);
-	/*
-	 * We do this explicitly after the caches have been drained above.
-	 */
-	uma_reclaim();
+	vm_uma_drain();
 	/*
 	 * Do whatever cleanup that the pmap code can.
 	 */
@@ -1508,6 +1522,14 @@
 	 * The pageout daemon is never done, so loop forever.
 	 */
 	while (TRUE) {
+		/*
+		 * If we got trouble for UMA, drain it.
+		 */
+		if (vm_uma_drain_needed) {
+			mtx_lock(&Giant);
+			vm_uma_drain();
+			mtx_unlock(&Giant);
+		}
 		vm_page_lock_queues();
 		/*
 		 * If we have enough free memory, wakeup waiters.  Do